In molding a food material such as ground raw beef to make flat hamburger patties the meat is customarily forced under pressure into a mold opening of the shape of the desired article, whether a flat round patty, a flat chop shaped patty or the like. This mold opening contains entrapped air which if not released either requires great pressure on the meat with consequent meat degradation or prevents a perfectly shaped patty being formed as the air tends to prevent the mold opening being completely filled with the food material.
One of the features of this invention is to provide an improved vent means that communicates with the mold opening during filling with the pressurized material so that air displaced by the entering pressurized charge of material can fill the mold without substantial resistance thereby permitting relatively low filling pressure and insuring that the molded articles will be well filled with the material.